MEMS scan controlled keystone and distortion correction

ABSTRACT

Briefly, in accordance with one or more embodiments, a MEMS scanned beam projector includes a light source to emit a light beam, a scanning platform to redirect the light beam impinging on the platform, and a display controller to control the light source and the scanning platform to cause the scanning platform to scan the light beam in a vertical direction and a horizontal direction in a scan pattern to project an image onto a projection surface. The display controller is configured to correct for image distortion in the projected image by providing a compensated drive signal to the scanning platform to compensate for the image distortion.

BACKGROUND

Projectors ordinarily are designed to produce a rectangular image whenprojecting onto a screen or other projection surface from an angle thatis perpendicular to or aligned with the normal of the projectionsurface. Image distortion occurs when a projector is aligned at adifferent, oblique angle to the projection surface, or when theprojection surface itself is angled, curved, or in some way irregularwith respect to the projector. The keystone effect is one of the mostcommon forms of distortion which results in an image that is trapezoidalrather than rectangular.

In order to address the keystoning problem, projectors typically utilizeeither optical or digital approaches to correct image distortion.Optical keystone correction involves a physical adjustment to theprojector lens so that the projector projects at a different angle thanit would be for a normal projection angle on a flat projection surface.Optical keystone correction generally is more effective if the projectoris sufficiently far from the projection surface. Digital keystonecorrection involves applying correction within digital video processingby converting and prescaling the image before the image is projected.One disadvantage of prescaling the video image is that the number ofindividual pixels in the image is reduced, thereby lowering the displayresolution and degrading the projected image quality.

DESCRIPTION OF THE DRAWING FIGURES

Claimed subject matter is particularly pointed out and distinctlyclaimed in the concluding portion of the specification. However, suchsubject matter may be understood by reference to the following detaileddescription when read with the accompanying drawings in which:

FIG. 1A is a diagram of an information handling system that includes amicroelectromechanical systems (MEMS) scanned beam projector to projectan image on a projection surface in accordance with one or moreembodiments;

FIG. 1B is a diagram of the information handling system of FIG. 1Aillustrating a table top use example in accordance with one or moreembodiments;

FIG. 2 is a diagram of the information handling system of FIG. 1A or 1Billustrating image distortion such as keystoning that may occur from anoblique projection axis with respect to the projection surface inaccordance with one or more embodiments;

FIG. 3 is a diagram of a MEMS scanned beam projector in accordance withone or more embodiments to project an image on a projection surface, andto detect and correct image distortion such as keystoning in accordancewith one or more embodiments;

FIG. 4 is a diagram of keystone correction of an image via modulation ofthe fast scan amplitude as a function of vertical scan position in theimage in accordance with one or more embodiments;

FIG. 5 is a diagram of keystone correction of an image via changing theinterpolator active region as a function of vertical scan position inaccordance with one or more embodiments;

FIG. 6 is a diagram of aspect correction of an image that has beenkeystone corrected via reduction of the MEMS vertical scan angle;

FIG. 7 are diagrams of a MEMS vertical ramp drive voltage for regularprojection and a corresponding MEMS constant velocity profile inaccordance with one or more embodiments;

FIG. 8 is a diagram of correction of horizontal line spacing viamodification of a vertical ramp that does not have a constant verticalvelocity in accordance with one or more embodiments;

FIG. 9 is a diagram of a MEMS vertical ramp velocity profile and driveamplitude with linearly increasing velocity in accordance with one ormore embodiments;

FIG. 10 is a diagram of a MEMS vertical ramp velocity profile and driveamplitude with exponentially increasing velocity in accordance with oneor more embodiments;

FIG. 11 is a diagram of a MEMS vertical ramp velocity profile and driveamplitude with a parabolically changing velocity in accordance with oneor more embodiments;

FIG. 12 is a diagram of a MEMS vertical ramp velocity profile and driveamplitude with a hyperbolic, piece-wise linear, and asymmetrical notchvelocity in accordance with one or more embodiments;

FIG. 13 is a diagram of a method to calibrate or otherwise adaptivelydetect and correct for image distortion in a projected image inaccordance with one or more embodiments;

FIG. 14A and FIG. 14B are diagrams of an example grid pattern andexample fiducials, respectively, to detect for image distortion in aprojected image in accordance with one or more embodiments;

FIG. 15 is a block diagram of an information handling system having aprojector to provide MEMS laser beam display utilizing MEMS scancontrolled keystone and distortion correction in accordance with one ormore embodiments;

FIG. 16 is an isometric view of an information handling system thatincludes a MEMS laser beam display utilizing MEMS scan controlledkeystone and distortion correction in accordance with one or moreembodiments.

FIG. 17 is a diagram of a vehicle that includes a MEMS laser beamdisplay utilizing MEMS scan controlled keystone and distortioncorrection deployed in a head-up display (HUD) in accordance with one ormore embodiments;

FIG. 18 is a diagram of eyewear that includes a MEMS laser beam displayutilizing MEMS scan controlled keystone and distortion correctiondeployed in a head-mounted display (HMD) in accordance with one or moreembodiments; and

FIG. 19 is a diagram a gaming apparatus in accordance with one or moreembodiments.

It will be appreciated that for simplicity and/or clarity ofillustration, elements illustrated in the figures have not necessarilybeen drawn to scale. For example, the dimensions of some of the elementsmay be exaggerated relative to other elements for clarity. Further, ifconsidered appropriate, reference numerals have been repeated among thefigures to indicate corresponding and/or analogous elements.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth to provide a thorough understanding of claimed subject matter.However, it will be understood by those skilled in the art that claimedsubject matter may be practiced without these specific details. In otherinstances, well-known methods, procedures, components and/or circuitshave not been described in detail.

In the following description and/or claims, the terms coupled and/orconnected, along with their derivatives, may be used. In particularembodiments, connected may be used to indicate that two or more elementsare in direct physical and/or electrical contact with each other.Coupled may mean that two or more elements are in direct physical and/orelectrical contact. However, coupled may also mean that two or moreelements may not be in direct contact with each other, but yet may stillcooperate and/or interact with each other. For example, “coupled” maymean that two or more elements do not contact each other but areindirectly joined together via another element or intermediate elements.Finally, the terms “on,” “overlying,” and “over” may be used in thefollowing description and claims. “On,” “overlying,” and “over” may beused to indicate that two or more elements are in direct physicalcontact with each other. However, “over” may also mean that two or moreelements are not in direct contact with each other. For example, “over”may mean that one element is above another element but not contact eachother and may have another element or elements in between the twoelements. Furthermore, the term “and/or” may mean “and”, it may mean“or”, it may mean “exclusive-or”, it may mean “one”, it may mean “some,but not all”, it may mean “neither”, and/or it may mean “both”, althoughthe scope of claimed subject matter is not limited in this respect. Inthe following description and/or claims, the terms “comprise” and“include,” along with their derivatives, may be used and are intended assynonyms for each other.

Referring now to FIG. 1A, a diagram of an information handling systemthat includes a microelectromechanical (MEMS) scanned beam projector toproject an image on a projection surface in accordance with one or moreembodiments will be discussed. As shown in FIG. 1A, an informationhandling system 100 may include a projector 110 such as a MEMS basedscanned beam projector to project an image 116 onto a projection surface118. In some embodiments, information handling system 100 may include amechanism 112 to redirect the image 116 out of information handlingsystem 100 and onto projection surface 118 when information handlingsystem 100 is positioned in a vertical or nearly vertical position.Mechanism 112 may be a simple first surface flat mirror or a compoundmirror with optic power or alternatively may be a compound free formoptic with nil or one or more mirrored surfaces. Alternatively,projector 110 may project the image 116 directly from a surface of theinformation handling system 100 without using a mechanism 112 toredirect the projected image 116. In some embodiments, informationhandling system 100 may include a kickstand 114 to position theinformation handling system 100 and hold it steady when the informationhandling system 100 is placed on the projection surface 118 duringviewing of the image 116, for example where the projection surface 118is a table or desktop. In other embodiments, projection surface 118might be a wall with the information handling system 100 set flat on atable or desktop with mechanism 112 redirecting the projected image ontoa wall. In other embodiments, a user may hold the information handlingsystem 100 in the user's hand during projection of the image 116 ontoprojection surface 118. It should be noted that information handlingsystem 100 may comprise a handheld device such as a smartphone or tabletthat includes a projector 110, or alternatively information handlingsystem 100 may simply comprise a standalone projector device thatincludes a projector 110. Furthermore, projector 110 may comprise a MEMSbased scanned beam projector such as shown in and described with respectto FIG. 3, below. If the projected image 116 is projected at an obliqueangle with respect to the projection surface 118, the projected imagemay be distorted with a keystone effect. Such image distortion is shownin and described with respect to FIG. 2, below.

FIG. 1B is a diagram of the information handling system illustrating atable top use example in accordance with one or more embodiments. Theembodiment of information handling system 100 shown in FIG. 1B issubstantially similar to the embodiment of information handling system100 of FIG. 1A, except FIG. 1B illustrated an example of usinginformation handling system 100 on a support surface 122 such as a tabletop, and the projected image 116 is projected onto a vertical projectionsurface 118 such as a wall or a projection screen. Other example uses ofthe information handling system 100 similarly may be deployed, forexample where information handling system 100 is mounted on a ceilingand the projected image 116 is projected onto a vertical projectionsurface 118 such as a wall or a projection screen, and the scope of theclaimed subject matter is not limited in this respect.

Referring now to FIG. 2, a diagram of the information handling system ofFIG. 1A or FIG. 1B illustrating image distortion such as keystoning thatmay occur from an oblique projection axis with respect to the projectionsurface in accordance with one or more embodiments will be discussed. Asshown in FIG. 2, the projected image 116 may suffer image distortionsuch as keystoning if the image 116 is projected at an angle that isdifferent than normal with respect to the plane or surface of projectionsurface 118. Such distortion in the projected image 116 may includehorizontal stretching at the distal end 210 of the image 116 withrespect to the proximal end 212 of the image. The resulting image 116 asshown in FIG. 2 is a trapezoidally shaped image 116 rather than arectangularly shaped image 116. For more extreme projection angles awayfrom normal, and/or for smaller throw ratios of the projected image 116,where throw ratio is the ratio of the distance from the projector 110 tothe projection surface 118 to the width of the projected image 116, theresulted image distortion becomes more extreme. The image distortion mayalso include a change in the aspect ratio of the projected image 116.For example, if the image 116 is a 16:9 image, the image distortioncauses the aspect ratio of the projected image 116 to no longer be a16:9 aspect ratio even if trapezoid distortion in the image iscompensated for resulting in a rectangular keystone-corrected image. Inaddition, the image distortion may result in vertical stretching of theimage at the distal end 210 of the image 210 with respect to theproximal end 212 of the image. With vertical stretching imagedistortion, the horizontal line spacing in the image changes based onvertical position along the image. In one or more embodiments, asdiscussed herein, the operation of a MEMS based scanned beam projector110 may be adjusted to correct for one or more of these three imagedistortion artifacts without adversely affecting the resolution orquality of the projected image. Such a MEMS based scanned beam projector110 is shown in and described with respect to FIG. 3, below. In someembodiments, the information handling system 100 may include a camera120 to detect distortion of the projected image 116 to calibrate imagedistortion correction and/or to continually and dynamically alter theimage distortion correction with varying distortion as discussed withrespect to FIG. 13, below.

Referring now to FIG. 3, a diagram of a MEMS scanned beam projector inaccordance with one or more embodiments to project an image on aprojection surface, and to detect and correct image distortion such askeystoning in accordance with one or more embodiments will be discussed.Although FIG. 3 shows a MEMS scanned beam projector 110 for purposes ofexample and discussion, it should be noted that the subject matterdiscussed herein may be utilized with displays other than a scanned beamdisplay, and the scope of the claimed subject matter is not limited inthis respect. As shown in FIG. 3, the projector 110 may comprise a lightsource 310, which may be a laser light source such as a laser or thelike, capable of emitting a beam 312 which may comprise a laser beam.The beam 312 impinges on a scanning platform 314 which may comprise amicroelectromechanical (MEMS) based scanning platform or the like, andreflects off of scanning mirror 316 to generate a controlled output beam324. A horizontal drive circuit 318 and a vertical drive circuit 320modulate the direction in which scanning mirror 316 is deflected tocause output beam 324 to generate a raster scan (or scan pattern) 326,thereby creating a displayed image 116 on a projection surface 118. Itshould be noted that although a raster scan is shown and discussedherein as one example scan pattern for purposes of discussion andexample, other scanning patterns likewise may be utilized other than araster scan, for example a Lissajous pattern, and the scope of theclaimed subject matter is not limited in this respect. A displaycontroller 322 controls horizontal drive circuit 318 and vertical drivecircuit 320 by converting pixel information of the displayed image intolaser modulation synchronous to the scanning platform 314 to write theimage information as displayed image 116 based upon the position of theoutput beam 324 in raster scan (or scan pattern) 326 and thecorresponding intensity and/or color information at the correspondingpixel in the image 116. Display controller 322 may also control othervarious functions of projector 110. It should be noted that the MEMSscanning platform is not limited to a single scanning mirror system. Insome embodiments, the scanning platform may comprise multiple mirrors toeffect fully or at least in in part the deflection expected in a certainaxis. In such a case, the drive circuitry would be distributed betweenthe multiple mirrors for the plane or axis of deflection. Furthermore,the mirrors in the MEMS scanning platform may be actuated eitherelectromagnetically, electrostatically, or in a hybrid or other mannerfor each of the axes of deflection. The MEMS scanning platform describedherein is not a limitation of the claimed subject matter.

In one or more particular embodiments, the projector 110 as shown inFIG. 3 may comprise a pico-display developed by Microvision, Inc., ofRedmond, Wash., USA, referred to as PicoP®. In such embodiments, thelight source 310 of such a pico-display may comprise one red, one green,and one blue laser, with a lens near the output of the respective lasersthat collects the light from the laser and provides a very low numericalaperture (NA) beam at the output. It should be noted that although thelight source 310 discussed herein for purposes of example includes ared, a green, and a blue light source (RGB), light source 310alternatively may include various other colors, both in the visibleand/or in the invisible light spectrum, for example any color of lasershaving wavelengths ranging from infrared to near ultraviolet orultraviolet, and the scope of the claimed subject matter is not limitedin this respect. The light from the lasers may then be combined withdichroic elements into a single white beam 312. Using a beam splitterand/or basic fold-mirror optics, the combined beam 312 may be relayedonto a mirror 316 of a biaxial MEMS scanning platform 314 that scans theoutput beam 324 in a raster scan (or scan pattern) 326. Modulating thelasers synchronously with the position of the scanned output beam 324may create the projected image 116. In one or more embodiments theprojector 110, or engine, may be disposed in a single module known as anIntegrated Photonics Module (IPM), which in some embodiments may be 7millimeters (mm) in height and less than 5 cubic centimeters (cc) intotal volume, although the scope of the claimed subject matter is notlimited in these respects.

In one or more embodiments, the projector 110 may include a camera 120or other image detecting device to capture at least a portion of theprojected image 116 to facilitate the determination whether any keystoneimage distortion exists. The image data captured by camera 120 may beprovided to display controller 322 to provide for image distortioncorrection by altering the operation of scanning platform 314 asdiscussed in further detail herein. In some embodiments, light source310 may include an invisible light source such as an infrared lightsource that may project an infrared beam or component of beam 324 aspart of image 116. Such a beam may be invisible so as to not benoticeable by the user during viewing of image 116. The invisible lightportion of image 116 may be detected by camera 120 as part of a imagedistortion calibration or correction process as discussed further hereinwith respect to FIG. 13, below. A camera 120 or other sensor may operateas a feedback mechanism to inform the display controller 322 or otherprocessor about the extent of geometric distortion seen in the projectedimage 116. In one or more embodiments, information handling system 100without a camera 120 or without other image also may correct fordistortion in the projected image 116, for example if the feedback ofoblique projection is acquired from inertial sensors in the informationhandling system 100. In such an example, information handling system 100may assume that projection surface 118 is always planar such as a table,wall, projection screen, or a similar planar surface. In one embodiment,information handling system 100 may include a kick-stand with multiplestops or catches to change the tilt angle of information handlingsystem. In such an embodiment, the a readout from inertial sensorsreadout may facilitate distortion compensation applied by the methodsand techniques described herein, for example where the angular positionof the information handling system 100 yields the angle of projection ofthe projected image 116 along with the height of the exit aperture fromthe support surface to be used to determine the amount of expected orpreviously measured image distortion.

In one or more embodiments, projector 110 may couple to or otherwise maybe integrated within the information handling system 100. An application328 may be executed on information handling system 326 for example toprovide image or video information to projector 110, and/or optionallyto assist with the image distortion correction performed by projector110, although the scope of the claimed subject matter is not limited inthese respects. A first example of controlling scanning platform 314 tocorrect image distortion is shown in and described with respect to FIG.4, below.

Referring now to FIG. 4, a diagram of keystone correction of an imagevia modulation of the fast scan amplitude as a function of vertical scanposition in the image in accordance with one or more embodiments will bediscussed. As shown in FIG. 4, a keystoned version 414 of the image 116may be corrected by altering the raster scan (or scan pattern) 326wherein the horizontal amplitude of the raster scan (or scan pattern)326 may be altered as a function of the vertical scan position of thebeam 324. Since the distal end 210 of the keystoned version 414 of theimage 116 may be stretched horizontally with respect to the proximal end212, the amplitude of the horizontal scan of scanning platform 314 maybe reduced at vertical positions 410 corresponding to the distal end 210of the image. The horizontal amplitude of the raster scan (or scanpattern) 326 may be varied in a manner to remove the trapezoidal shapeof the keystoned version 414 of the image 116. In some embodiments, thehorizontal amplitude of the raster scan (or scan pattern) 326 may beincreased at vertical positions 412 corresponding to the proximal end212 of the image if there is sufficient headroom in the deflection ofthe scanning platform 314 to allow for increased amplitudes. In anyevent, the display controller 322 may change the output of thehorizontal drive circuit 318 to vary the horizontal amount of deflectionof the scanning platform 314. As a result, the horizontal stretchingcomponent of the keystone distortion may be compensated by modulatingthe fast scan sinusoidal amplitude of the MEMS scanning platform 314linearly as a function of vertical position. With a typical verticalrefresh rate of 60 Hertz (Hz), the modulation profile may be periodic atthe vertical refresh rate of 60 Hz with the fast (horizontal) scan anglebeing reduced as the trapezoidal distortion widens. The result is ahorizontally compensated version 416 of image 116 with the trapezoidaldistortion reduced or eliminated from the image 116. An alternativeapproach to remove the trapezoidal distortion is shown in and describedwith respect to FIG. 5, below.

Referring now to FIG. 5, a diagram of keystone correction of an imagevia changing the interpolator active region as a function of verticalscan position in accordance with one or more embodiments will bediscussed. As an alternative to varying the amplitude of the fast(horizontal) scan amplitude of the scanning platform 314, FIG. 5 showshow video path interpolation may be utilized to remove trapezoidaldistortion from a keystoned version 414 of the image. Projector 110 maycomprise a laser beam scanning (LBS) display system that modulates thelasers to paint pixels on the trajectory of MEMS scanning platform 314.In a typical 720p system, the nominal horizontal resonant frequency ofthe scanning platform 314 is approximately 27 kHz, and full horizontalscan line is traversed in about 18.5 microseconds (μs). If the sample(pulse) rate of the lasers is 150 MHz, then projector 110 placesapproximately 2,200 laser pulses on a single horizontal scan line in asingle direction in the active video region that does not include thehorizontal blanking periods. Display controller 322 may include a videopath interpolator operating in the scan domain to keep track of theinstantaneous scan position and to interpolate between neighboring input(source) pixels to determine the appropriate output pixel intensity forthe currently displayed pixel. The output may be oversampled as an inputof 1,280 horizontal pixels from the image source are converted into2,200 output laser pulses. In order to compensate for the trapezoidalimage distortion due to the keystone effect, the interpolator can becommanded by display controller 322 to change its starting and endingpositions along the horizontal lines of the raster scan (or scanpattern) 326 as a function of vertical position, and to adjust theinterpolation rate accordingly as shown in FIG. 5. The start and endpositions of the interpolator along the raster scan (or scan pattern)326 are represented by line 510 and line 512. The active region 514 ofthe interpolator exists between line 510 and line 512 such thatinterpolation operates at different horizontal positions of raster scan(or scan pattern) 326 as a function of vertical position. Thus, thestart and stop positions of the interpolator may be a function of thevertical position along the raster scan (or scan pattern) 326 in such amanner as to reduce or eliminate the trapezoidal distortion in thekeystoned version 414 of the image to result in a trapezoid compensatedversion 416 of the image. Compensation of the trapezoidal component ofthe keystone distortion of image 116 may result in rectangular versionof the image 116 with horizontal stretching removed. Compensation of theaspect ratio of the image may be performed as shown in an described withrespect to FIG. 6, below.

Referring now to FIG. 6, a diagram of aspect correction of an image thathas been keystone corrected via reduction of the MEMS vertical scanangle will be discussed. Once the trapezoidal distortion resulting fromthe horizontal stretching component of the keystone effect iscompensated for in image 116, the resulting version 610 of the image 116may have a different aspect ratio than the original source image, forexample resulting in a version 610 of the image that is too tall in thevertical direction. In order to provide an aspect ratio of the projectedimage 116 that matched the aspect ratio of the original source image,the vertical height of the image 116 may be reduced by reducing theamplitude of the vertical ramp of the MEMS scanning platform 314. Anuncompensated ramp 614 is shown on the left hand side of FIG. 6 having astandard ramp height wherein the display controller 322 causes thevertical drive circuit 320 to provide a drive voltage shown in ramp 614to displace the scanning platform 314 to a maximum downward deflectionwith a maximum negative drive voltage 616 to linearly ramp up to amaximum upward deflection with a maximum positive drive voltage 618. Themaximum downward deflection and the maximum upward deflection ofscanning platform may be reduced by reducing the magnitudes of themaximum negative drive voltage and the maximum positive drive voltage tovalues as shown at voltage 620 and voltage 622 to provide a compensatedramp 624. As a result, amplitude of displacement of the scanningplatform 314 is reduced to result in an aspect ratio compensationversion 612 of image 116. For example, of the aspect ratio of theoriginal source image is 16:9, then the aspect ratio of the aspect ratiocompensated version 612 of image 116 is also 16:9 or nearly 16:9,although the scope of the claimed subject matter is not limited in thisrespect.

Referring now to FIG. 7, diagrams of a MEMS vertical ramp drive voltagefor regular projection and a corresponding MEMS constant velocityprofile in accordance with one or more embodiments will be discussed.After applying compensation as shown in FIG. 4 or FIG. 5, and as shownin FIG. 6, the resulting image 116 is rectangular with a correct aspectratio. The image, however, still may have image distortion as thevertical line spacing may vary with vertical position. The scanningplatform 314 typically is driven in a vertical direction with a sawtoothramp voltage with constant velocity over the active video region, forexample as shown in FIG. 7. The upper diagram 710 shows the MEMSscanning platform 314 vertical ramp drive voltage for non-compensationprojection, with the amplitude normalized to maximum field of view (FOV)of projector 110. The lower diagram 712 shows a constant velocityprofile for movement of the MEMS scanning platform 314 over the activevideo area indicated by the dotted vertical lines normalized to thecenter of the displacement of the MEMS scanning platform 314.Compensation of the vertical spacing of the horizontal scan lines may beachieved by altering the velocity of the vertical displacement of theMEMS scanning platform 314 as shown in and described with respect toFIG. 8, below.

Referring now to FIG. 8, a diagram of correction of horizontal linespacing via modification of a vertical ramp that does not have aconstant vertical velocity in accordance with one or more embodimentswill be discussed. As shown in FIG. 8, an uncompensated version 810 ofthe raster scan (or scan pattern) 326 on the left hand side of FIG. 8may have vertical spacing of the horizontal scan lines at regions 812corresponding to the distal end 210 of the image 116 that is greaterthan the vertical spacing of the horizontal lines at regions 814corresponding to the proximal end 212 of the image 116. A vertical rampvoltage for scanning platform 314 having a linear velocity is shown atplot 816. By changing the rate of change of the vertical ramp voltagefor the scanning platform 314 over the vertical sweep of the scanningplatform 314 as shown at plot 818, for example to provide a slowervelocity at regions 812, the velocity of the vertical displacement ofthe scanning platform 314 may be altered such that the vertical spacingof the horizontal scan lines is constant, or nearly constant, over theentirety of the raster scan (or scan pattern) 326 to provide avertically compensated version 820 of the raster scan (or scan pattern)326 as shown in the right hand side of FIG. 8.

Referring now to FIG. 9 through FIG. 12, diagrams of a various MEMS rampvelocity profiles and drive amplitudes in accordance with one or moreembodiments will be discussed. In one or more embodiments, displaycontroller 322 is capable of driving MEMS scanning platform 314 in avertical direction with various velocity profiles. Display controller322 may drive MEMS scanning platform 314 to compensate for imagedistortion resulting from various shapes of the projection surface 118other than a flat, planar surface as shown in FIG. 1A or FIG. 1B. Forexample, image distortion caused by uneven, curved, spherical, or otherirregular surfaces can be compensated in a manner substantially similarto compensating for keystone image distortion by driving MEMS scanningplatform 314 in such a manner as to correct for the resulting imagedistortion. FIG. 9 shows an example ramp profile having a linearlyincreasing velocity. FIG. 10 shows an example MEMS vertical rampvelocity profile and drive amplitude with exponentially increasingvelocity for compensating projecting image 116 onto a curved projectionsurface 118. FIG. 11 shows an example MEMS vertical ramp velocityprofile and drive amplitude with a parabolically changing velocity forcompensating projecting image 116 onto a spherical projection surface118. FIG. 12 shows an example MEMS vertical ramp velocity profile anddrive amplitude with a hyperbolic 1201, piece-wise linear 1202,asymmetrical notch 1203 velocity for compensating projecting image 116onto various other irregular or non-planar projection surfaces. Itshould be noted that these are merely a few example vertical driveamplitudes and velocity profiles, and the scope of the claimed subjectmatter is not limited in these respects.

Referring now to FIG. 13, a diagram of a method to calibrate orotherwise adaptively detect and correct for image distortion in aprojected image in accordance with one or more embodiments will bediscussed. It should be noted that FIG. 13 illustrates one particularorder and number of the operations of method 1300, whereas in otherembodiments method 1300 may include more of fewer operations in variousother orders, and the scope of the claimed subject matter is not limitedin these respects. In one or more embodiments, an ideal velocity profilefor driving MEMS scanning platform 314 may be automatically determinedvia image processing techniques. The automatically determined velocityprofile may be utilized to generate an appropriate velocity profile withwhich to drive the MEMS scanning platform 314 to image distortioncompensation or correction of the projected image 116. Method 1300illustrates One such method using an overhead camera in single, offlinecalibration process, or alternatively in a dynamic auto-correctionprocess.

At block 1310, an image 116 may be projected onto the display surface118. At block 1312, projector 110 projects a grid pattern or fiducialscoincident with the projected image 116. In one or more embodiments,light source 310 may include an infrared light source or infrared laserbeam to project the grid pattern or fiducials, either as a separateoffline test pattern, or an out-of-band test pattern that is temporallyseparated from the visible image, or an in-band test pattern that istemporally coincident with the visible image 116 without interferingwith the user experience in viewing the image 116. Examples of a gridpattern and fiducials are shown in and described with respect to FIG.14A and FIG. 14B, below. An image of the grid pattern or fiducials maybe captured at block 1314, for example using camera 120 which maycomprise an infrared camera in some embodiments where the grid patternor fiducials are projected using an infrared light or laser beam.Display controller 322 may then resolve the captured image of the gridpattern or fiducials into world space at block 1316 to determine thetopology of projection surface 118. Having knowledge of the topology ofprojection surface 118, at block 1318 display controller 322 maydetermine any needed image distortion correction due to the topology ofprojection surface 118. Display controller 322 may then apply imagedistortion correction at block 1320 to the MEMS drive signal to modifythe scan profile of MEMS scanning platform 314. In some embodiments,display controller 322 may continually monitor image distortion anddynamically apply image distortion correction at block 1322, for exampleby continually executing one or more of the blocks of method 1300,although the scope of the claimed subject matter is not limited in thisrespect. Example grid patterns and fiducials utilized in method 1300 areshown in and described with respect to FIG. 14A and FIG. 14B, below.

Referring now to FIG. 14A and FIG. 14B, diagrams of an example gridpattern and example fiducials, respectively, to detect for imagedistortion in a projected image in accordance with one or moreembodiments will be discussed. In embodiments where projector 110includes a visible or infrared (IR) camera 120 projecting image 116 atan unknown angle of incidence with respect to the projection surface118, grid pattern 1410 may be displayed on the projection surface 118.As the projection and camera fields of view (FOVs) are fixed and knowna-priori, the grid pattern 1410 may then be captured by the camera 120,and a view transform computed to resolve the image from camera spaceinto world space, for example as discussed with respect to FIG. 13,above. In some embodiments, the same image processing functions may berun to allow for online or dynamic velocity auto-profiling in the eventthe projection angle of incidence with respect to the projection surface118 changes.

In general, the extent of image keystoning or other image distortion inalso may be determined using various other techniques. For example, insome embodiments light source 310 may include an infrared (IR) laserdiode (LD) is in the optical path, and the projected infrared beam iscombined with the red, green, and blue (RGB) beam 312 and scanned out bythe MEMS mirror 316 via beam 324. Virtual measurement fiducials 1412 maybe placed in the projected light beam 324 by pulsing the IR LD when thephase and/or position of MEMS scanning platform 314 corresponds to thefour corners 1414 of the field of view (FOV) of projector 110, sparselocations along the frame 1416 of the FOV, and/or sparse locations alongthe left edge 1418 and right edge 1420 of the FOV, among other examples.

Using depth detection methods, for example a scanned beam time of flight(TOF) method that utilizes a single photodetector in place of a camera120, the distance from the IR virtual fiducials 1412 to the projector110 may be determined. Without interrupting the projected RGB videocontent of image 116, for example without using any calibration cycles,an auto-profiler routine running on display controller 322 may determinethe correction needed to be applied and dynamically modify the scanprofile to project a distortion corrected or compensated image 116. Itshould be noted that the IR fiducial approach is substantially similarto a process using a camera 120, the view transforms utilized in an IRapproach will be a function of distance from the projection source.Other various approaches may be utilized to determine a suitable MEMSdrive and velocity profile, and the scope of the claimed subject matteris not limited in these respects.

Referring now to FIG. 15, a block diagram of an information handlingsystem having a MEMS laser beam display utilizing MEMS scan controlledkeystone and distortion correction in accordance with one or moreembodiments will be discussed. Although information handling system 100represents one example of several types of computing platforms, such asa smartphone, tablet, hand held gaming device, personal computer or thelike, information handling system 100 may include more or fewer elementsand/or different arrangements of elements than shown in FIG. 15, and thescope of the claimed subject matter is not limited in these respects.Information handling system 100 may utilize the MEMS laser beam displayof FIG. 3 for example as a projector 110 to project an image 116 on adisplay surface 118, and further to implement MEMS scan controlledkeystone and distortion correction as described herein, although thescope of the claimed subject matter is not limited in these respects.

In one or more embodiments, information handling system 100 may includean applications processor 1510 and a baseband processor 1512.Applications processor 1510 may be utilized as a general purposeprocessor to run applications and the various subsystems for informationhandling system 100. Applications processor 1510 may include a singlecore or alternatively may include multiple processing cores, for examplewherein one or more of the cores may comprise a digital signal processoror digital signal processing core. Furthermore, applications processor1510 may include a graphics processor or coprocessor disposed on thesame chip, or alternatively a graphics processor coupled to applicationsprocessor 1510 may comprise a separate, discrete graphics chip.Applications processor 1510 may include on board memory such as cachememory, and further may be coupled to external memory devices such assynchronous dynamic random access memory (SDRAM) 1514 for storing and/orexecuting applications during operation, and NAND flash 1516 for storingapplications and/or data even when information handling system 100 ispowered off. In one or more embodiments, instructions to operate orconfigure the information handling system 100 and/or any of itscomponents or subsystems to operate in a manner as described herein maybe stored on an article of manufacture comprising a non-transitorystorage medium. In one or more embodiments, the storage medium maycomprise any of the memory devices shown in and described herein,although the scope of the claimed subject matter is not limited in thisrespect. Baseband processor 1512 may control the broadband radiofunctions for information handling system 100. Baseband processor 1512may store code for controlling such broadband radio functions in a NORflash 1518. Baseband processor 1512 controls a wireless wide areanetwork (WWAN) transceiver 1520 which is used for modulating and/ordemodulating broadband network signals, for example for communicatingvia a Third Generation (3G) or Fourth Generation (4G) network or thelike or beyond, for example a Long Term Evolution (LIE) network. TheWWAN transceiver 1520 couples to one or more power amps 1522respectively coupled to one or more antennas 1524 for sending andreceiving radio-frequency signals via the WWAN broadband network. Thebaseband processor 1512 also may control a wireless local area network(WLAN) transceiver 1526 coupled to one or more suitable antennas 1528and which may be capable of communicating via a Wi-Fi, Bluetooth, and/oran amplitude modulation (AM) or frequency modulation (FM) radio standardincluding an IEEE 802.11 a/b/g/n standard or the like. It should benoted that these are merely example implementations for applicationsprocessor 1510 and baseband processor 1512, and the scope of the claimedsubject matter is not limited in these respects. For example, any one ormore of SDRAM 1514, NAND flash 1516 and/or NOR flash 1518 may compriseother types of memory technology such as magnetic memory, chalcogenidememory, phase change memory, or ovonic memory, and the scope of theclaimed subject matter is not limited in this respect.

In one or more embodiments, applications processor 1510 may drive adisplay 1530 for displaying various information or data, and may furtherreceive touch input from a user via a touch screen 1532 for example viaa finger or a stylus. An ambient light sensor 1534 may be utilized todetect an amount of ambient light in which information handling system100 is operating, for example to control a brightness or contrast valuefor display 1530 as a function of the intensity of ambient lightdetected by ambient light sensor 1534. One or more cameras 1536 may beutilized to capture images that are processed by applications processor1510 and/or at least temporarily stored in NAND flash 1516. Furthermore,applications processor may couple to a gyroscope 1538, accelerometer1540, magnetometer 1542, audio coder/decoder (CODEC) 1544, and/or globalpositioning system (GPS) controller 1546 coupled to an appropriate GPSantenna 1548, for detection of various environmental propertiesincluding location, movement, and/or orientation of information handlingsystem 100. Alternatively, controller 1546 may comprise a GlobalNavigation Satellite System (GNSS) controller. Audio CODEC 1544 may becoupled to one or more audio ports 1550 to provide microphone input andspeaker outputs either via internal devices and/or via external devicescoupled to information handling system via the audio ports 1550, forexample via a headphone and microphone jack. In addition, applicationsprocessor 1510 may couple to one or more input/output (I/O) transceivers1552 to couple to one or more I/O ports 1554 such as a universal serialbus (USB) port, a high-definition multimedia interface (HDMI) port, aserial port, and so on. Furthermore, one or more of the I/O transceivers1552 may couple to one or more memory slots 1556 for optional removablememory such as secure digital (SD) card or a subscriber identity module(SIM) card, although the scope of the claimed subject matter is notlimited in these respects. In one or more embodiments, the MEMS laserbeam display may 110 be coupled to one or more of the I/O transceivers1552 and may be integrated within a housing of information handlingsystem 100 or alternatively may be disposed exterior to the housing,although the scope of the claimed subject matter is not limited in theserespects.

Referring now to FIG. 16, an isometric view of an information handlingsystem that includes a MEMS laser beam display 110 utilizing MEMS scancontrolled keystone and distortion correction in accordance with one ormore embodiments will be discussed. The information handling system 1600of FIG. 16 may represent a tangible embodiment of the informationhandling system 100 of FIG. 15. Information handling system 1600 maycomprise any of several types of computing platforms, including cellphones, personal digital assistants (PDAs), netbooks, notebookcomputers, internet browsing devices, tablets, pads, and so on, and thescope of the claimed subject matter is not limited in these respects. Inthe example shown in FIG. 16, information handling system 1600 maycomprise a housing 1610 to house MEMS laser beam display 110 asdiscussed herein, for example to provide a scanned output beam 1620 toproject an image and/or to provide MEMS scan controlled keystone anddistortion correction as discussed herein. Information handling system1600 optionally may include a display 1612 which may be a touch screendisplay, keyboard 1614 or other control buttons or actuators, a speakeror headphone jack 1616 with optional microphone input, control buttons1618, memory card slot 1620, and/or input/output (I/O) port 1622, orcombinations thereof. Furthermore, information handling system 1600 mayhave other form factors and fewer or greater features than shown, andthe scope of the claimed subject matter is not limited in theserespects.

Referring now to FIG. 17, a diagram of a vehicle that includes a MEMSlaser beam display utilizing MEMS scan controlled keystone anddistortion correction deployed in a head-up display (HUD) in accordancewith one or more embodiments will be discussed. In the embodiment shownin FIG. 17, the MEMS laser beam display 110 may be deployed in a vehicle1710 such as in the dashboard of the automobile 1710, and which mayproject an image 1720 that may be viewable by an operator or passengerof the vehicle. Although FIG. 17 shows one example deployment of a MEMSlaser beam display 110 utilizing MEMS scan controlled keystone anddistortion correction as a display projector, other types of deploymentslikewise may be provided, and the scope of the claimed subject matter isnot limited in this respect.

Referring now to FIG. 18, a diagram of eyewear that includes a MEMSlaser beam display utilizing MEMS scan controlled keystone anddistortion correction deployed in a head-mounted display (HMD) inaccordance with one or more embodiments will be discussed. In theembodiment shown in FIG. 18, the MEMS laser beam display beam scanner110 may be deployed in eyewear 1810 or other head worn device, forexample attached to a frame of the eyewear 1810, and which may projectan image 1820 that may be viewable by the wearer of the eyewear 1810.Although FIG. 18 shows one example deployment of a MEMS laser beamdisplay 110 utilizing MEMS scan controlled keystone and distortioncorrection in a display projector, other types of deployments likewisemay be provided, and the scope of the claimed subject matter is notlimited in this respect.

Referring now to FIG. 19, a diagram a gaming apparatus in accordancewith one or more embodiments will be discussed. Gaming apparatus 1900includes buttons 1902, display 1910, and projector 110. In someembodiments, gaming apparatus 1900 is a standalone apparatus that doesnot need a larger console for a user to play a game. For example, a usermay play a game while watching display 1910 and/or the projected contentat 116. In other embodiments, a use may watch a larger screen tetheredto the console in combination with watching display 1910 and/orprojected content at 116.

Although the claimed subject matter has been described with a certaindegree of particularity, it should be recognized that elements thereofmay be altered by persons skilled in the art without departing from thespirit and/or scope of claimed subject matter. It is believed that thesubject matter pertaining to MEMS scan controlled keystone anddistortion correction and many of its attendant utilities will beunderstood by the forgoing description, and it will be apparent thatvarious changes may be made in the foam, construction and/or arrangementof the components thereof without departing from the scope and/or spiritof the claimed subject matter or without sacrificing all of its materialadvantages, the form herein before described being merely an explanatoryembodiment thereof, and/or further without providing substantial changethereto. It is the intention of the claims to encompass and/or includesuch changes.

What is claimed is:
 1. A MEMS scanned beam projector, comprising: alight source to emit a light beam; a scanning platform to redirect thelight beam impinging on the platform; and a display controller tocontrol the light source and the scanning platform to cause the scanningplatform to scan the light beam in a vertical direction and a horizontaldirection in a scan pattern to project an image onto a projectionsurface; wherein the display controller is configured to correct forimage distortion in the projected image by providing a compensated drivesignal to the scanning platform to compensate for the image distortion,and wherein the display controller is configured to compensate forvariation in horizontal line spacing in the projected image bymodulating the scanning platform in the vertical direction with anon-constant velocity.
 2. The MEMS scanned beam projector as claimed inclaim 1, wherein the display controller is configured to compensate forhorizontal stretching in the projected image due to geometric distortionby modulation of the scanning platform in the horizontal direction as afunction of vertical scan position to reduce or eliminate the horizontalstretching.
 3. The MEMS scanned beam projector as claimed in claim 1,wherein the display controller is configured to compensate forhorizontal stretching in the projected image due to geometric distortionby modifying a start position and a stop position of video pathinterpolation as a function of vertical scan position to reduce oreliminate the horizontal stretching.
 4. The MEMS scanned beam projectoras claimed in claim 1, wherein the display controller is configured tocompensate for aspect ratio distortion in the projected image byreducing an amplitude of vertical displacement of the scanning platform.5. The MEMS scanned beam projector as claimed in claim 1, wherein thenon-constant velocity comprises a linearly increasing velocity, anexponentially increasing velocity, a parabolically changing velocity, ahyperbolically changing velocity, a piece-wise linearly changingvelocity, or an asymmetric notch velocity, or a combination thereof. 6.The MEMS scanning platform as claimed in claim 1, wherein: the displaycontroller is configured to cause the scanning platform to project agrid pattern or one or more fiducial as part of the projected image; anda camera to detect the grid pattern or the one or more fiducials;wherein the display controller is further configured to determine thecorrection needed for the projected image based at least in part on thedetected grid pattern or the one or more fiducials.
 7. The MEMS scanningplatform as claimed in claim 6, wherein: the light source includes aninfrared light source to emit an infrared light as a component of thelight beam; the display controller is configured to project the gridpattern or the one or more fiducials using the infrared light; thecamera is an infrared camera to detect the grid pattern or the one ormore fiducials as a component of the light beam.
 8. The MEMS scanningplatform as claimed in claim 7, wherein the display controller isconfigured to detect a distance from the MEMS scanned beam projector tothe projection surface using time of flight analysis on the infraredlight, and the display controller utilizes the detected distance todetermine a compensated drive signal to provide to the scanningplatform.
 9. A method to compensate for image distortion in an imageprojected by a MEMS scanned beam projector, the method comprising:redirecting a light beam from a light source impinging on a scanningplatform; controlling the light source and the scanning platform tocause the scanning platform to scan the light beam in a verticaldirection and a horizontal direction in a scan pattern to project animage onto a projection surface; correcting for image distortion in theprojected image by providing a compensated drive signal to the scanningplatform to compensate for the image distortion; and compensating forvariation in horizontal line spacing in the projected image bymodulating the scanning platform in the vertical direction with anon-constant velocity.
 10. The method as claimed in claim 9, furthercomprising: compensating for horizontal stretching in the projectedimage due to geometric distortion by modulation of the scanning platformin the horizontal direction as a function of vertical scan position toreduce or eliminate the horizontal stretching.
 11. The method as claimedin claim 9, further comprising: compensating for horizontal stretchingin the projected image due to geometric distortion by modifying a startposition and a stop position of video path interpolation as a functionof vertical scan position to reduce or eliminate the horizontalstretching.
 12. The method as claimed in claim 9, further comprising:compensating for aspect ratio distortion in the projected image byreducing an amplitude of vertical displacement of the scanning platform.13. The method as claimed in claim 9, wherein the non-constant velocitycomprises a linearly increasing velocity, an exponentially increasingvelocity, a parabolically changing velocity, a hyperbolically changingvelocity, a piece-wise linearly changing velocity, or an asymmetricnotch velocity, or a combination thereof.
 14. The method as claimed inclaim 9, further comprising: causing the scanning platform to project agrid pattern or one or more fiducial as part of the projected image;detecting the grid pattern or the one or more fiducials with a camera;and determining the correction needed for the projected image based atleast in part on the detected grid pattern or the one or more fiducials.15. The method as claimed in claim 14, wherein: the light sourceincludes an infrared light source to emit an infrared light as acomponent of the light beam, and the grid pattern or the one or morefiducials are projected using the infrared light; detecting the gridpattern or the one or more fiducials with the camera, wherein the cameracomprises an infrared camera.
 16. The method as claimed in claim 15,further comprising: detecting a distance from the MEMS scanned beamprojector to the projection surface using time of flight analysis on theinfrared light; and utilizing the detected distance to determine acompensated drive signal to provide to the scanning platform.